368 On the Solar Eclipse predicted ly Tholes. 



system is too much at variance with the astronomical fact 

 to be entitled to any ciedit. 



It has been remarked by Dr. Hallcv (Phil. Trans, vol. 

 xxix. p. 243), that " though twenty-eighl eclipses of the 

 *' sun happen in eighteen years, and ei-ght ])ass through the 

 *' parallel ol London, yet since March iO\h, \ 140, no total 

 "eclipse has been seen in that metropolis." Indeed, so rare 

 is this phaenomenon in any particular country, that its oc- 

 currence, when well auihcnlicatcd, may be considered as an 

 spra w hich is less liable to mistakes or confusion, than any 

 other event recorded in history. All atlempts at imposition 

 or deceit are ea>ilv detec'ted by our knowledge ot astronomy: 

 and ihc unintentional errors of ihe historian are soon recti- 

 fied and adjusted. On this account, and as the fact of the 

 eclipse is so confidently related by Herodotus (indeed, its 

 sinoular coincidence with the battle will ever render it me- 

 moiable in history), I would place the termination of the 

 war between Alyattes and Cyaxares, iu ihe year 6(0 B. C; 

 and, if llie other events of that period, as related by the 

 historian, cannot be reconciled to this date, I should attri- 

 bute the confusion to the want of authentic documents and 

 information at the time that \\\c history was written. 



I have bef'ire observed, that all these calculations have 

 been made from the Tahles Astronomiques^ lately published 

 in France: which tables have since been adapted to the me- 

 ridian of Greenwich, and to astronomical time, by Mr. 

 VincCj and inserted by him in the third volume of his Sy- 

 stem of Astronomy*. In these tables are given the secular 

 variations in the moon's mean longitude, mean anomaly, 

 and mean distance from her node, as deduced from the for- 

 mulae of M.Laplace. It is with much deference that I 

 presume to question the accuracy of the results obtained 

 by means of those formulae ; but, as the present subject is 

 in a great measure connected with that inquiry, 1 shall 

 briefly state my reasons for offering a doubt upon that point. 



* It is to be regretted, tJiat Mr. Vince did not adapt his tables to the Eng- 

 lish system of (hro/i'jlcgy likewise. For the years before Christ, according to 

 the English modt- c;f computation, exceed by unity the coresponding year* 

 given by the Fieiuh chronologists: since they make the year of Christ equal 

 to 0, whereas the English reckon it as 1 B. C — The French altto assume the 

 vear l.'>82 iis the date of the reformation of the calendar ; whereas, in Eng- 

 iaiKl, that event did not take place liil the year 175l'. 



Without a proper attention w these circumstai.ces, we may be led into an 

 error of one whole year, in tiie calculation of the places of the heavenly 

 bodies for any period prior to the Ch.ristian xra ; and into an error of ten 

 or eleven days in our calculations for that spice of time which is included 

 betwtou October 5th, 1582. and September Mt^, 1752. 



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